This paper presents the explanation system for NEOMYCIN* , a medical consultation program. A consultation program plays the role of an expert to assist a user in solving a problem. An explanation of strategy describes the plan the program is using to reach a solution. Such an explanation is usually concrete, referring to aspects of the current problem situation. Abstract explanations articulate a general principle, which can be applied in different situations; such explanations arc useful in teaching and in explaining by analogy. We describe the aspects of NEOMYCIN that make abstract strategic explanations possible-the representation of strategic knowledge explicitly and separately from domain knowledge--and demonstrate how this representation can be used to generate explanations.